Adrenaline and Noradrenaline have similar functions (not opposing or antagonistic). Both the hormones increase the heart beat, the strength of heart contraction and the rate of respiration.
Calcitonin is hypocalcemic while parathormone is hypercalcemic.
Insulin is hypoglycemic while glucagon is hyperglycemic.
Somatocrinin induces release of GH while somatostatin inhibits the release of GH.